1. Field of the Invention
The present invention relates to an image reading apparatus having a document reading function, such as an image scanner, a facsimile machine, and a copying machine.
2. Description of the Related Art
Image scanners, facsimile machines, and copying machines can operate in various reading modes. FIG. 8 is a vertical cross-sectional diagram illustrating a conventional image reading apparatus. The image reading apparatus illustrated in FIG. 8 is an image scanner. The image scanner illustrated in FIG. 8 can operate in a first reading mode for reading an image of a document (i.e., original) P101 placed on a platen glass 101 and in a second reading mode for reading an image of each document (i.e., original) P102 stacked on a document feeder tray 103.
In the first reading mode, a driving unit (not illustrated) shifts a first reading unit 102 from a position X1 to a position X2. The first reading unit 102 scans the document P101 placed on the platen glass 101. In the second reading mode, a separation roller 105 continuously separates sheets of the document P102 stacked on the tray 103 and feeds separated sheets one by one to a first feed roller pair 107. A second feed roller pair 108 can receive a document sheet from the first feed roller pair 107 and carry the sheet to a discharge tray 104. A second reading unit 120 fixed in a document carrying section and the first reading unit 102 stopped at a home position can scan both a reverse surface and a front surface of the carried document sheet.
More specifically, according to the second reading mode, the separation roller 105 and a separating pad 106 can separate one sheet (i.e., the lowest sheet) from the stacked document P102. The first feed roller pair 107 carries a separated sheet. The second reading unit 120 reads an image of a reverse surface (i.e., upper surface) of the carried document sheet. The first reading unit 102 stopped at the position X1 reads an image of a front surface (i.e., lower surface) of the document sheet.
The document sheet P102 is discharged to the discharge tray 104 by the second feed roller pair 108 after their front and reverse images have been read. Then, the separation roller 105 and the separating pad 106 separate the next sheet of the document P102. The first feed roller pair 107 carries the next sheet. The first reading unit 102 and the second reading unit 120 read front and reverse surface images of the carried document sheet. This kind of conventional image reading apparatus is discussed in Japanese Patent Application Laid-Open No. 11-27507.
The above-described conventional image scanner enables a user to flexibly use both the first reading mode (i.e., a mode for scanning a document placed on a platen glass) and the second reading mode (i.e., a mode for scanning a document stacked on the document feeder section) as mentioned above.
However, the apparatus body tends to become larger because of the mechanism required for realizing plural functions. When the first reading mode is selected to scan a photographic document or a large document (e.g., a map), a user is required to open and close a relatively heavy cover of an automatic document feeder (ADF) in which the separation roller and the feed roller pairs are provided. The work for opening and closing the cover is not convenient for a user.